Psychologists and anthropologists have long observed how children in Mexico and Guatemala help around the house. Not only do they begin doing household chores earlier than children in the US, they continue to do so as they grow up, and they don't have to be told to do so, or even asked to. They happily contribute their work on their own as a matter of course.

They help do the laundry, help cook meals, help wash dishes. And they often do chores without being told. No gold stars or tie-ins to allowances needed.

In one study, psychologist Barbara Rogoff and her colleagues interviewed moms in Guadalajara, Mexico, who had indigenous ancestry. The researchers asked the moms what their children, who were all between the ages of 6 and 8, do to help around the house and how often they do these tasks voluntarily.

The study — published in 2014 — contains some of the most remarkable quotes I have ever seen in a research article.

For example, one mother said her 8-year-old daughter comes home from school and declares: "Mom, I'm going to help you do everything." Then she "picks up the entire house, voluntarily," the study reported.

"Another time, the mom comes home from work, and she's really tired," says Rogoff of the University of California, Santa Cruz. "She just plops herself down on the couch. And the daughter, says, 'Mom you're really tired, but we need to clean up the house. How about I turn on the radio and I take care of the kitchen and you take care of the living room and we'll have it all cleaned up?' "

Volunteering to help is such an important trait in kids that Mexican families even have a term for it: acomedido.

"For example, one mom told us: 'When my toddler was doing the dishes, at the beginning, the water was all over the place, but I would allow my son to the dishes because that's how he learned,' " she says.